Repairs to two roof valleys
Valley one
A scaffold will need to be erected around the front door area so the tiles to both sides of the valley to the width of 2/3 Meters can be removed.
The valley roof tiles will need to be moved onto the scaffold to undertake this work as a complete job and not doing things in small sections from a cherry picker.
The lead on the valley then needs to be removed.
New felt will have to be placed down the entire length of the timber valley boarding and new lead work will need to be applied.
Or fibreglass
If the lead was replaced by fibreglass, felt to the valley timber will not be needed.
The exposed timber batons will need to be removed and larger sections of felt around need to be laid from the ridge to the eve, then new batons will need to be secured.
Relay the roof tiles and replace any damaged ones.
Cement the edges to the valley.
Dump old tiles/batons etc.
Valley two
Maybe accessible from a balcony with a small scaffold tower.